mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-27 05:00:15 +00:00
9605ca6c08
http://sourceware.org/ml/libc-alpha/2013-07/msg00001.html This patch starts the process of supporting powerpc64 little-endian long double in glibc. IBM long double is an array of two ieee doubles, so making union ibm_extended_long_double reflect this fact is the correct way to access fields of the doubles. * sysdeps/ieee754/ldbl-128ibm/ieee754.h (union ibm_extended_long_double): Define as an array of ieee754_double. (IBM_EXTENDED_LONG_DOUBLE_BIAS): Delete. * sysdeps/ieee754/ldbl-128ibm/printf_fphex.c: Update all references to ibm_extended_long_double and IBM_EXTENDED_LONG_DOUBLE_BIAS. * sysdeps/ieee754/ldbl-128ibm/e_exp10l.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/e_expl.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/ldbl2mpn.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/math_ldbl.h: Likewise. * sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/strtold_l.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/x2y2m1l.c: Likewise.
124 lines
3.4 KiB
C
124 lines
3.4 KiB
C
/* Round to int long double floating-point values without raising inexact.
|
|
IBM extended format long double version.
|
|
Copyright (C) 2006-2013 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
/* This has been coded in assembler because GCC makes such a mess of it
|
|
when it's coded in C. */
|
|
|
|
#include <math.h>
|
|
#include <math_private.h>
|
|
#include <fenv.h>
|
|
#include <math_ldbl_opt.h>
|
|
#include <float.h>
|
|
#include <ieee754.h>
|
|
|
|
|
|
long double
|
|
__nearbyintl (long double x)
|
|
{
|
|
fenv_t env;
|
|
static const long double TWO52 = 4503599627370496.0L;
|
|
union ibm_extended_long_double u;
|
|
u.ld = x;
|
|
|
|
if (fabs (u.d[0].d) < TWO52)
|
|
{
|
|
double high = u.d[0].d;
|
|
feholdexcept (&env);
|
|
if (high > 0.0)
|
|
{
|
|
high += TWO52;
|
|
high -= TWO52;
|
|
if (high == -0.0) high = 0.0;
|
|
}
|
|
else if (high < 0.0)
|
|
{
|
|
high -= TWO52;
|
|
high += TWO52;
|
|
if (high == 0.0) high = -0.0;
|
|
}
|
|
u.d[0].d = high;
|
|
u.d[1].d = 0.0;
|
|
math_force_eval (u.d[0]);
|
|
math_force_eval (u.d[1]);
|
|
fesetenv (&env);
|
|
}
|
|
else if (fabs (u.d[1].d) < TWO52 && u.d[1].d != 0.0)
|
|
{
|
|
double high, low, tau;
|
|
/* In this case we have to round the low double and handle any
|
|
adjustment to the high double that may be caused by rounding
|
|
(up). This is complicated by the fact that the high double
|
|
may already be rounded and the low double may have the
|
|
opposite sign to compensate. */
|
|
feholdexcept (&env);
|
|
if (u.d[0].d > 0.0)
|
|
{
|
|
if (u.d[1].d > 0.0)
|
|
{
|
|
/* If the high/low doubles are the same sign then simply
|
|
round the low double. */
|
|
high = u.d[0].d;
|
|
low = u.d[1].d;
|
|
}
|
|
else if (u.d[1].d < 0.0)
|
|
{
|
|
/* Else the high double is pre rounded and we need to
|
|
adjust for that. */
|
|
|
|
tau = __nextafter (u.d[0].d, 0.0);
|
|
tau = (u.d[0].d - tau) * 2.0;
|
|
high = u.d[0].d - tau;
|
|
low = u.d[1].d + tau;
|
|
}
|
|
low += TWO52;
|
|
low -= TWO52;
|
|
}
|
|
else if (u.d[0].d < 0.0)
|
|
{
|
|
if (u.d[1].d < 0.0)
|
|
{
|
|
/* If the high/low doubles are the same sign then simply
|
|
round the low double. */
|
|
high = u.d[0].d;
|
|
low = u.d[1].d;
|
|
}
|
|
else if (u.d[1].d > 0.0)
|
|
{
|
|
/* Else the high double is pre rounded and we need to
|
|
adjust for that. */
|
|
tau = __nextafter (u.d[0].d, 0.0);
|
|
tau = (u.d[0].d - tau) * 2.0;
|
|
high = u.d[0].d - tau;
|
|
low = u.d[1].d + tau;
|
|
}
|
|
low = TWO52 - low;
|
|
low = -(low - TWO52);
|
|
}
|
|
u.d[0].d = high + low;
|
|
u.d[1].d = high - u.d[0].d + low;
|
|
math_force_eval (u.d[0]);
|
|
math_force_eval (u.d[1]);
|
|
fesetenv (&env);
|
|
}
|
|
|
|
return u.ld;
|
|
}
|
|
|
|
long_double_symbol (libm, __nearbyintl, nearbyintl);
|